Hybrid inorganic–organic solids form an interesting family of functional materials, where their functionalities are determined by both, the inorganic and organic building blocks. This study reports ...the intercalation of pyrazine in 2D copper nitroprusside, the crystal structure of the resulting hybrid solid and explores the scope of cryogenic X-ray photoelectron spectroscopy (XPS) to shed light on its electronic structure. In this material, the pyrazine molecule appears coordinated to Cu atoms from neighboring layers, to form the columns in the resulting 3D porous framework. Its crystal structure was solved and refined from the corresponding XRD powder pattern. XPS data, recorded under cryogenic conditions, provided fine details on the electronic structure of this hybrid solid. The binding energy values for the ligand atoms and the involved metals show a definite correlation with the structural data and FT-IR spectra. When XPS spectra were recorded at room temperature, a significant sample decomposition was observed. Three possible mechanisms for the sample damage during the XPS experiment are considered. The hybrid material under study is representative of a wide series of nanoporous solids obtained by intercalation of organic pillars between 2D inorganic solids.
Intercalation of pyrazine molecules between layers of copper nitroprussides, coordination environments for the metals in the resulting hybrid inorganic-organic solids and the N 1s XPS spectrum. Display omitted
•Inorganic – organic hybrid material.•Intercalation of Pyrazine in 2D layered copper nitroprusside.•Crystal structure of hybrid solid.•Cryogenic X-ray photoelectron spectroscopy.•Sample damage on the XPS experiment.
Existing image restoration models are typically designed for specific tasks and struggle to generalize to out-of-sample degradations not encountered during training. While zero-shot methods can ...address this limitation by fine-tuning model parameters on testing samples, their effectiveness relies on predefined natural priors and physical models of specific degradations. Nevertheless, determining out-of-sample degradations faced in real-world scenarios is always impractical. As a result, it is more desirable to train restoration models with inherent generalization ability. To this end, this work introduces the Out-of-Sample Restoration (OSR) task, which aims to develop restoration models capable of handling out-of-sample degradations. An intuitive solution involves pre-translating out-of-sample degradations to known degradations of restoration models. However, directly translating them in the image space could lead to complex image translation issues. To address this issue, we propose a model reprogramming framework, which translates out-of-sample degradations by quantum mechanic and wave functions. Specifically, input images are decoupled as wave functions of amplitude and phase terms. The translation of out-of-sample degradation is performed by adapting the phase term. Meanwhile, the image content is maintained and enhanced in the amplitude term. By taking these two terms are inputs, restoration models are able to handle out-of-sample degradations without fine-tuning. Through extensive experiments across multiple evaluation cases, we demonstrate the effectiveness and flexibility of our proposed framework.
The quantum anomalous Hall (QAH) insulator carries dissipation-free chiral edge current and thus provides a unique opportunity to develop energy-efficient transformative information technology. ...Despite promising advances, the QAH insulator has thus far eluded any practical applications. In addition to its low working temperature, the QAH state in magnetically doped topological insulators usually deteriorates with time in ambient conditions. In this work, we store three QAH devices with similar initial properties in different environments. The QAH device without a protection layer in air shows clear degradation and becomes hole-doped. The QAH device kept in an argon glovebox without a protection layer shows no measurable degradation after 560 h, and the device protected by a 3 nm AlO x protection layer in air shows minimal degradation with stable QAH properties. Our work shows a route to preserve the dissipation-free chiral edge state in QAH devices for potential applications in quantum information technology.
Sample degradation, in particular of biomolecules, frequently occurs in surface‐enhanced Raman spectroscopy (SERS) utilizing supported silver SERS substrates. Currently, thermal and/or photocatalytic ...effects are considered to cause sample degradation. This paper establishes the efficient inhibition of sample degradation using iodide which is demonstrated by a systematic SERS study of a small peptide in aqueous solution. Remarkably, a distinct charge separation‐induced surface potential difference is observed for SERS substrates under laser irradiation using Kelvin probe force microscopy. This directly unveils the photocatalytic effect of Ag‐SERS substrates. Based on the presented results, it is proposed that plasmonic photocatalysis dominates sample degradation in SERS experiments and the suppression of typical SERS sample degradation by iodide is discussed by means of the energy levels of the substrate under mild irradiation conditions. This approach paves the way toward more reliable and reproducible SERS studies of biomolecules under physiological conditions.
Biosample degradation significantly limits the application of surface enhanced Raman spectroscopy (SERS) and often causes mis‐assignments of spectra. Using iodide solutions not only suppresses sample degradation in SERS and provides signal similar to standard Raman spectra, it also provides insight into the photocatalytic mechanisms behind the degradation process.
Endoscopic pancreatic function tests are used to diagnose pancreatic diseases and are a viable source for the discovery of biomarkers to better characterize pancreatic disorders. However, pancreatic ...fluid (PF) contains active enzymes that degrade biomolecules. Therefore, we tested how preservation methods and time to storage influence the integrity and quality of proteins and nucleic acids.
We obtained PF from 9 subjects who underwent an endoscopic pancreatic function test. Samples were snap frozen at the time of collection; after 1, 2, and 4 hours on ice; or after storage overnight at 4°C with or without RNase or protease inhibitors (PIs). Electrophoresis and mass spectrometry analysis determined protein abundance and quality, whereas nucleic acid integrity values determined DNA and RNA degradation.
Protein degradation increased after 4 hours on ice and DNA degradation after 2 hours on ice. Adding PIs delayed degradation. RNA was significantly degraded under all conditions compared with the snap frozen samples. Isolated RNA from PF-derived exosomes exhibited similar poor quality as RNA isolated from matched PF samples.
Adding PIs immediately after collecting PF and processing the fluid within 4 hours of collection maintains the protein and nucleic acid integrity for use in downstream molecular analyses.
The ability to noninvasively detect the presence of species and assess physiological health by DNA and hormone analysis makes scat a valuable tool for ecology and conservation. We assessed factors ...associated with DNA and hormone degradation in a four‐season study that employed detection dogs to collect scats from maned wolf (Chrysocyon brachyurus) in the Brazilian Cerrado, a tropical savanna landscape mosaic. Fecal DNA sample viability was assessed by attempting polymerase chain reaction amplification of a mitochondrial DNA (mtDNA) locus (∼ 246 bp) and a nuclear DNA zinc finger protein gene (∼ 195 bp). We assessed how extraction method, environmental exposure, and amount of odor, moisture and diet items in the sample influenced DNA amplification and allelic dropout rates. Samples that amplified mtDNA were assayed for glucocorticoids and thyroid hormone. Amount of odor and moisture (indicating freshness) predicted mtDNA amplification success, as well as mean hormone levels. While factors related to sample condition were negatively correlated with lower mean hormone levels, samples comprised mainly of fruit had higher levels of glucocorticoids and lower levels of thyroid hormone, and we thus interpret this result as biologically meaningful. In summary, DNA and hormone degradation are predicted by measures of sample freshness, making the assessment of sample quality an important criterion for sample collection as well to manage measurement error in analyses of hormone concentration associated with environmental disturbance.
NMR-based metabolomics investigations of human biofluids offer great potential to uncover new biomarkers. In contrast to protocols for sample collection and biobanking, procedures for sample ...preparation prior to NMR measurements are still heterogeneous, thus compromising the comparability of the resulting data. Herein, we present results of an investigation of the handling of cerebrospinal fluid (CSF) samples for NMR metabolomics research. Origins of commonly observed problems when conducting NMR experiments on this type of sample are addressed, and suitable experimental conditions in terms of sample preparation and pH control are discussed. Sample stability was assessed by monitoring the degradation of CSF samples by NMR, hereby identifying metabolite candidates, which are potentially affected by sample storage. A protocol was devised yielding consistent spectroscopic data as well as achieving overall sample stability for robust analysis. We present easy to adopt standard operating procedures with the aim to establish a shared sample handling strategy that facilitates and promotes inter-laboratory comparison, and the analysis of sample degradation provides new insights into sample stability.
A common recommendation in the field of animal chemosignaling is to store and transport scent samples frozen, since they are likely to change with time and degrade due to bacterial activity inside ...the sample containers and the loss of the most volatile compounds. However, we still ignore the exact pattern of change or degradation for these types of samples. Here we experimentally tested the stability of primate scent samples during analytical procedures. For this purpose, we used swabs of naturally deposited glandular secretions from captive tamarins (Neotropical primates) analyzed by headspace gas chromatography-mass spectrometry. We successively extracted the samples by solid-phase microextraction, while controlling for the delay between extractions, and compared the number of compounds detected in the samples under each condition. We found that compounds were lost and transformed over time inside the sample vials. Such natural decay of scent signals is likely to contribute to the long term information transmitted. We found no evidence that long delays at room temperature affected sample chemical composition more than short delays. Nonetheless, we showed that repeated extraction of a sample increased the loss of compounds. The changes in sample chemical composition observed over time in this experiment support standard recommendation to avoid storing samples for long periods at room temperature and to extract each sample only once, in order to ensure optimum results.
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